A process of manufacturing a semiconductor device includes a process of forming a silicon-based insulating film such as a silicon oxide film (SiO2), a silicon nitride film (Si3N4), or the like, on a substrate such as a silicon wafer, i.e., an insulating film containing silicon, which is a predetermined element. The silicon oxide film is widely used as an insulating film or an interlayer film having a high insulation property and low permittivity. In addition, the silicon nitride film has a good insulation property, corrosion resistance, permittivity, film stress controllability, or the like, and is widely used as an insulating film, a mask film, a charge accumulation film, or a stress control film. Further, a technique of adding carbon (C) into the insulating film is also already known, and thus etching resistance of the insulating film can be improved.